The scientific methods used to assess biocompatibility and patient safety have been unchanged in decades, some techniques for 50 years. Currently, two-thirds of restorative dentistry is involved in replacing cavity restorations, because treatment has failed. Each year in the United States, approximately 25 million of these failures are due to postoperative pulp healing problems, including hypersensitivity, inflammation, pulp tissue necrosis, and a loss of pulp vitality. A biocompatibility testing method is needed to asses the ability of dental treatments to regenerate oral tissues. Legal, ethical, and safety guidelines severely limit the number and scope of clinical and animal research needed to evaluate the injury and healing associated with dental restorative procedures. In the last update of the biocompatibility screening guidelines (7405 and 10933) the International Organization for Standardization (ISO) recommended the development of new investigative approaches to serve as an alternative to live animal testing, but none have been developed so far. Every year, worldwide, millions of rodents and 57,000 non-human primates are used in animal biomedical research, mainly for biocompatibility screening during product testing. The purpose of this study is to develop a highly reproducible, and economical in vitro method for evaluating the biocompatibility and injurious effects of dental restorative procedures and materials. The long-term goal of this study is to incorporate the newly developed biocompatibility screening protocols into the ISO guidelines as an alternative to many live animal experiments. The following specific aims will be used to develop a novel biocompatibility assay for use in dentistry: 1: Test the hypothesis that in vitro rat incisors are a stable method to measure the injurious effects of dental restorative procedures on the pulp tissue. 2: Test the hypothesis that in vitro human teeth are a stable method to measure the injurious effects of dental restorative procedures on the pulp tissue. 3: Test the hypothesis that in vitro teeth provide comparable measures of pulp injury to restorative procedures in comparison with in vivo human teeth. 4: Test the hypothesis that Heat Shock Protein expression can be used as new assay endpoint for assessing biocompatibility.